[DTrace-devel] [PATCH 05/14] Support dirname() for addresses that are not DTrace pointers

[Kris Van Hees]

On Thu, Nov 03, 2022 at 03:52:17PM -0400, eugene.loh--- via DTrace-devel wrote:
> From: Eugene Loh <eugene.loh at oracle.com>
> 
> Signed-off-by: Eugene Loh <eugene.loh at oracle.com>

Reviewed-by: Kris Van Hees <kris.van.hees at oracle.com>

> ---
>  bpf/dirname.S                             | 17 ++++++++++------
>  test/unittest/funcs/tst.dirname_nonDPTR.d | 24 +++++++++++++++++++++++
>  test/unittest/funcs/tst.dirname_nonDPTR.r |  2 ++
>  3 files changed, 37 insertions(+), 6 deletions(-)
>  create mode 100644 test/unittest/funcs/tst.dirname_nonDPTR.d
>  create mode 100644 test/unittest/funcs/tst.dirname_nonDPTR.r
> 
> diff --git a/bpf/dirname.S b/bpf/dirname.S
> index e5795f06..7ff90b47 100644
> --- a/bpf/dirname.S
> +++ b/bpf/dirname.S
> @@ -21,6 +21,11 @@ dt_dirname :
>  	mov	SRC, %r1
>  	mov	DST, %r2
>  
> +	/*
> +	 * Copy src to dst for two reasons:
> +	 *   - to get the string length
> +	 *   - to have a copy that we can access directly
> +	 */
>  	/* r0 = bpf_probe_read_str(dst, STRSZ + 1, src) */
>  	mov	%r1, DST
>  	lddw	%r2, STRSZ
> @@ -49,8 +54,8 @@ dt_dirname :
>  	sub	LEN, 1
>  	/* if (len s< 0) goto Lslash */
>  	jslt	LEN, 0, .Lslash
> -	/* if (src[len] == '/') goto L1 */
> -	mov	%r0, SRC
> +	/* if (dst[len] == '/') goto L1 */
> +	mov	%r0, DST
>  	add	%r0, LEN
>  	ldxb	%r0, [%r0+0]
>  	and	%r0, 0xff
> @@ -65,8 +70,8 @@ dt_dirname :
>  	sub	LEN, 1
>  	/* if (len s< 0) goto Ldot */
>  	jslt	LEN, 0, .Ldot
> -	/* if (src[len] != '/') goto L2 */
> -	mov	%r0, SRC
> +	/* if (dst[len] != '/') goto L2 */
> +	mov	%r0, DST
>  	add	%r0, LEN
>  	ldxb	%r0, [%r0+0]
>  	and	%r0, 0xff
> @@ -81,8 +86,8 @@ dt_dirname :
>  	sub	LEN, 1
>  	/* if (len s< 0) goto Lslash */
>  	jslt	LEN, 0, .Lslash
> -	/* if (src[len] == '/') goto L3 */
> -	mov	%r0, SRC
> +	/* if (dst[len] == '/') goto L3 */
> +	mov	%r0, DST
>  	add	%r0, LEN
>  	ldxb	%r0, [%r0+0]
>  	and	%r0, 0xff
> diff --git a/test/unittest/funcs/tst.dirname_nonDPTR.d b/test/unittest/funcs/tst.dirname_nonDPTR.d
> new file mode 100644
> index 00000000..dab80655
> --- /dev/null
> +++ b/test/unittest/funcs/tst.dirname_nonDPTR.d
> @@ -0,0 +1,24 @@
> +/*
> + * Oracle Linux DTrace.
> + * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
> + * Licensed under the Universal Permissive License v 1.0 as shown at
> + * http://oss.oracle.com/licenses/upl.
> + */
> +
> +#pragma D option quiet
> +#pragma D option destructive
> +
> +BEGIN
> +{
> +	/* "/foo/bar///baz/" */
> +	system("printf '\x2f\x66\x6f\x6f\x2f\x62\x61\x72\x2f\x2f\x2f\x62\x61\x7a\x2f' > /dev/null 2>&1");
> +}
> +
> +syscall::write:entry
> +/ppid == $pid/
> +{
> +	printf("|%s|\n", dirname((void *)arg1));
> +	exit(0);
> +}
> +
> +ERROR { exit(1); }
> diff --git a/test/unittest/funcs/tst.dirname_nonDPTR.r b/test/unittest/funcs/tst.dirname_nonDPTR.r
> new file mode 100644
> index 00000000..bb8afc9d
> --- /dev/null
> +++ b/test/unittest/funcs/tst.dirname_nonDPTR.r
> @@ -0,0 +1,2 @@
> +|/foo/bar|
> +
> -- 
> 2.18.4
> 
> 
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